Mobile machine, for example, earthworking machines, construction machines, transport machines, and the like, are used for a wide variety of purposes. During these uses, it is common to periodically shut down the prime power source, e.g., an engine, either deliberately or inadvertently. For example, it may be necessary to power down the engine if the operator must leave the mobile machine frequently. As another example, the load demands on a mobile machine, such as an earthworking or construction machine, may result in periodic stalling of the engine.
In the above cases, it logically becomes necessary to engage a start-up process to start the engine after each shut down. These start-up sequences, however, may result in a problem if, for some reason, operator control of the steering of the mobile machine is not in synchronization with the actual steering angle of the mobile machine. This lack of synchronization may cause the mobile machine to suddenly move, i.e., "lurch", in an undesired direction during the start-up process. For example, the steering wheel of the mobile machine may appear to the operator to be set for straight ahead travel, but the actual steering angle of the mobile machine may be set for either a right or left direction, thus causing the mobile machine to suddenly move either to the right or the left to the surprise of the operator.
Attempts in the past have been made to resolve this problem. For example, in U.S. Pat. No. 3,795,285, Scholl et al. (Scholl) discloses a steering system for an articulated mobile machine which determines if the actual angle of steering differs from the desired angle of steering beyond a threshold value during the start-up process. The system prevents the engine from starting in response to the threshold being exceeded.
However, many auxiliary systems on a mobile machine, for example, hydraulic systems on a work machine, receive power from the engine. Therefore, if the engine is not allowed to start, these auxiliary systems will not function. In some circumstances, it may be desired to provide power to the auxiliary systems even though the mobile machine is not aligned for steering. Thus, it may be desired to allow the engine to start, yet still prevent the mobile machine from moving until the steering is aligned. For example, a wheel loader engine may stall while a fully loaded bucket is in a raised position. It would be desirable to have control of the hydraulic system to finish dumping and lowering the bucket even though the wheel loader is not allowed to move so that any potential problems from an offset center of gravity of the wheel loader are avoided when movement is allowed.
The present invention is directed to overcoming one or more of the problems as set forth above.